Functional tests:

Short term

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Long term

Jett was born bleh [from Z]
Jett was born bleh [from -0500]

Logan was born bleh [from Z]
Logan was born bleh [from -0400]

Ryan was born bleh [from Z]
Ryan was born bleh [from -0500]

Other formats

Date only: (you shouldn't see this).

Errors

Bad (letters): (this should be displayed).
Bad (numbers): (this should be displayed).
Bad (missing): (this should be displayed).

Parsing unit tests:

Ryan was born...
[from Z]
[from -00:00]
[from -05:00]
[from -0500]
[from +09:00]
[from +0900]

Wording unit tests:

[-1 sec]
[0 sec]
[30 sec]
[45 sec]
[90 sec]
[120 sec]
[45 min]
[89 min]
[90 min]
[120 min]
[1380 min]
[696 hours]
[30 days]
[190 days]
[366 days]
[1095 days]